BUENOS AIRES, Argentina (JTA) – Alberto Nisman was murdered, the attorney general for Argentina’s Criminal Appeals Court said — the first suggestion by the country’s judicial branch that the AMIA special prosecutor’s mysterious death may have been an assassination.

Ricardo Saenz in a letter to the judges on Thursday called for a federal investigation of the case involving Nisman, who was found shot dead in his Buenos Aires apartment on Jan. 18, 2015. There has been no official cause of death.

A federal magistrate “has the broadest jurisdiction to clarify which of all the assumptions” involving Nisman’s death is accurate, Saenz wrote.

The Criminal Appeals Court will hold a hearing on March 18 to decide what court should be given jurisdiction over the case. Murder cases are handled by the federal courts.

Nisman’s family has claimed he was murdered. His former wife, Sandra Arroyo Salgado, has called for a federal investigation,

Saenz again put the spotlight on Diego Lagomarsino, the IT engineer who worked with Nisman at the AMIA special unit and admitted to lending Nisman the gun that ended his life. The versions about the presence of the gun at Nisman’s apartment are “contradictory,” Saenz wrote.

In his opinion, Saenz also referred to the results of tests on the gun said to have killed Nisman as elements that negate the possibility that the special prosecutor committed suicide.

Nisman, who was Jewish, was found hours before he was to present evidence to Argentine lawmakers that President Cristina Fernandez de Kirchner covered up Iran’s role in the 1994 attack on the AMIA Jewish center in Buenos Aires that left 85 dead and hundreds wounded.